In an electrohydraulic valve control (EHVS) the oil control valves are electrically activated for the charge-cycle valves. Due to the incidental power loss in the output stages of the control unit, the output stages are deposed from the actual motor control unit, for example, disposed near the cylinder head and thereby in the spatial vicinity of the oil control valves. The end stages can thus be integrated into an output stage unit and comprise its own control functions as an “intelligent output stage unit”. The intelligent output stage unit communicates via a data bus with the motor control unit. The separate assembly of the intelligent EHVS-output stage unit requires a real time capable communication interface, preferably in the form of a serial data bus (for example: CAN, TTCAN, Flexray, or another data bus system).
The breakdown of the data bus leads to a breakdown of the valve control, which leads to a shutdown of the motor and thus a stoppage of the vehicle. In this case, there is no longer a chance for a “limp home” function, i.e. no limited functionality for a trip home or to the repair shop.
The task of the invention at hand is therefore to allow at least a limited operation of the internal combustion engine when the data bus breaks down between the motor control unit and the output stage unit.